This invention relates to the web manufacturing industry. Materials like paper, films and various laminates are typically manufactured as a continuous sheet or web of material. During the processing of a continuous web, the web is handled by cylindrical rolls and cut into continuous strips. This cutting is typically required for downstream handling or for producing a final product such as a roll of tape.
The invention is a slitting device. The slitting device includes a circular blade with a sharp cutting edge on the periphery and a blade actuator this slitting device is referred to as a knife holder. The knife holder typically includes a means of extending and translating the circular blade into an anvil which is cylindrical in shape and has a cutting edge located on the periphery of each end. This translation develops a force between the anvil and the blade the invention pertains to this force.
The prior art cited in application Ser. No. 12/672,561 Chilcott teaches a translation mechanism which includes a strain gauge (Page 15 Lines 8-10). This placement of the strain gauge requires that connecting wires extend thru the side shift mechanism. Thus the mechanism cannot be removed without disconnecting these wires. Additionally, this mounting scheme requires flexure of the mechanism in a position that also requires rigid support of the circular slitting blade. This latter requirement causes a tradeoff between rigid support and force sensing accuracy.
Other prior art is cited which includes U.S. Pat. No. 8,707,838 Dienes. This patent teaches driving two circular blades against each other using a motor for each blade. An adaptive control assembly which includes both motors is used to maintain constant pressure against the overlap of the two blades. The specific use of strain gauges is not taught. This means that the force determination could be determined by the amount of current used to move each blade. One of the problems with this type of device is that the cutting edge (regardless of the force determination function) must be moved and in some cases both the top and bottom blade are moved. This will result in a variable width of material being cut. Most slitting applications require exacting control of the slitting location transversely along the width of the web.
An additional prior art example from Deines is U.S. Pat. No. 6,877,412. This patent teaches the use of a pressure sensor in conjunction with a pneumatic cylinder to determine and monitor side force. This patent however does not specifically teach a means of controlling the side force. Again in this example the pressure sensor is an integrated part of the blade support and translation mechanism and so requires removing the wires during blade maintenance.
Lastly, prior art U.S. Pat. No. 5,453,867 Ichikawa is considered. This patent specifically teaches the use of a strain gauge to determine side shift force. However, no method of actively controlling side shift force is provided. Additionally, an integrated translation mechanism is not contemplated.
Some of the embodiments of the invention include a means of determining that the blade and anvil are in contact. As can be imagined as the blade is sharpened it decreases in diameter, since the vertical extension of the blade is fixed relative to the anvil, at some point the blade and anvil will no longer touch. This causes the blade to move over the anvil edge instead of into the side. This condition results in an incorrect side force reading and the controller sets an alarm indicating maintenance is required. This is indicated in FIG. 12 at step 3004.
It is the objective of this invention to address these issues included in the above prior art by providing an improved mechanism and method of slitting materials while being processed in the form of a moving web. Additionally, each and every issue in the prior art is not addressed by each embodiment. In fact some embodiments may not address any of the prior art issues mentioned above.